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Test Description

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Check MAP sensor output voltage to ECM. This voltage, without engine running, represents a barometric reading to the ECM.
  2. Apply 10 in. Hg vacuum to MAP sensor should cause voltage to be about 1.2 volts less than voltage in step 1). Upon applying vacuum to sensor, the change in voltage should be immediate. A slow voltage change indicates a faulty sensor.
  3. Check vacuum hose to sensor for leaks or restriction. Be sure no other vacuum devices are connected to MAP hose.
Fig 1: MAP Output Check Flow Chart & Schematic
G120828
Fig 2: MAP Output Check
GB0048647
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